1. Field of the Invention
This invention relates to a two-circuit cooling system for an internal combustion engine and a fluid pump used therein.
2. Description of the Prior Art
Cooling systems for use in vehicles and other machinery have been utilized for many years. The most common type used for vehicle engines is a high temperature circuit which effects the cooling of the motor proper. This circuit includes an engine water jacket, a circulation pump and a radiator. Three patents which describe various types of such engine cooling systems include: U.S. Pat. No. 2,760,468 issued to Dolza in 1956; U.S. Pat. No. 3,080,857 issued to Middendorf in 1963; and U.S. Pat. No. 3,425,400 issued to Scheremberg in 1969. With the advent of supercharged and turbocharged engines, an auxiliary low temperature circuit was added to cool the incoming air to the engine, and if necessary, the lubricating oil. Such an auxiliary circuit included an air-to-water heat exchanger, a circulation pump, a radiator and if necessary, an oil-to-water heat exchanger. U.S. Pat. No. 3,439,657 issued to Gratzmuller in 1969 teaches such a system. Up until now, virtually all dual cooling systems employed a pair of fluid pumps, primarily because each circuit operated at different temperatures and at different flow rates. The use of two pumps adds to the complexity and cost of the cooling system as well as decreasing the engine's overall efficiency.
Now a unique coolant pump has been invented which allows a two-circuit cooling system to be operational using a single pump.